The popularity of prairies is blooming.

Growing appreciation of natural landscapes and concerns about reducing water, fertilizer and pesticide use have made native prairie plants one of the hottest trends in horticulture.

But too often what was meant to be a prairie-like mix of grasses and wildflowers ends up as a weed patch.

"The No. 1 problem in wildflower establishment is competition from weeds," said Roch Gaussoin, a University of Nebraska horticulturist.

Gaussoin, USDA-Agricultural Research Service Rangeland Scientist Bob Masters and agronomy graduate student Dan Beran have tested a herbicide treatment that beats out the weeds, making native wildflower and grass establishment simpler and more reliable.

Because prairies mix grasses and broadleaf wildflowers, herbicides have not been useful for controlling weeds in prairie plantings. Most herbicides selectively target either grasses or broadleaved plants like wildflowers, or non-selectively kill both.

In this Institute of Agriculture and Natural Resources work to restore degraded grasslands, researchers found that Plateau (imazapic) herbicide, recommended for control of broadleaves and grasses, was different.

"We saw the chemistry of this herbicide was unique because in addition to not harming native grasses, it didn't affect composites or legumes, plant families that include many prairie wildflowers," Gaussoin said.

This led to Beran's graduate research project focusing partially on wildflower establishment.

Beran initially screened six native wildflowers and grasses for their tolerance to the herbicide and developed an application rate that could be recommended specifically for wildflower establishment.

After seeding wildflowers, Beran sprayed Plateau on the plots to control weeds, including crabgrass, lambsquarters and redroot pigweed. Four weeks after treatment, he measured the percentage of weed control and wildflower emergence. Fourteen months after planting, Beran recorded wildflower density and flowering.

Herbicide treatment improved wildflower establishment in weedy sites and increased flower density in the second growing season, Beran found.

"This isn't a miracle treatment, though," Beran said. "Some species aren't very tolerant of the herbicide, so some wildflowers are injured. The prairie grasses generally are more tolerant than the wildflowers."

Wildflowers that respond well to the herbicide include blanketflower, purple coneflower, purple prairie-clover, Illinois bundleflower, partridge pea, leadplant, black-eyed Susan and upright prairie coneflower.

The best use for the herbicide is for large areas, such as acreÜages, roadsides and golf course roughs, where some damage can be tolerated, Beran said.

"What the herbicide does is reduce weed competition and the amount of time it takes to get wildflowers established," Beran said. In a small urban wildflower plot, hand-weeding may be just as timely and less expensive.

The herbicide is expensive, about $360 per gallon, and currently is available only in gallon or larger quantities. A gallon goes a long way - the application rate is 2 to 4 ounces per acre.

Dave Stock, president of Stock Seeds Inc. at Murdock, was instrumental in pushing Plateau producer American Cyanamid to develop packaging aimed at smaller applicators. Stock Seeds is one of the nation's premier commercial resources for prairie grass and wildflower seeds.

American Cyanamid will market Prairie Pack, a $50 to $60 two-acre-sized Plateau application, next spring. This package will be great for prairie enthusiasts, homeowners and landscape professionals, Stock said.

Stock uses the Plateau treatment on his 1,500 acres of grasses and wildflowers. He views the IANR research on prairie establishment as an important partnership with both the herbicide developers and growers like himself who apply the research.

"It was really helpful to us to take advantage of both the prairie restoration and wildflower establishment research and apply it on a larger scale here," Stock said.

American Cyanamid and the Nebraska Turfgrass Foundation help fund this research.

-Monica Manton Norby

Graduate students Dan Beran (left) and Fernando Rivas-Pantoja inspect a mixed plot of wildflowers and prairie grasses near Ashland treated with imazapic herbicide to control weeds.

Beran (white shirt, foreground) discusses IANR research on ways to control weeds while establishing prairie plantings during a tour at NU's Agricultural Research Development Center near Mead.